This week on Castle, the show remembers Nathan Fillion is a geek god and acts accordingly. The episode could have just been subtitled "Hey, did you hear Firefly turned ten? Anniversary episode anyone?"

This episode was the most delightfully geeky thing I've seen on television in a long time, and I often watch The Big Bang Theory. It was also a love letter to sci-fi fans in general, and Firefly fans in particular. It was almost impossible to count all the references to sci-fi, fantasy, and good old fashioned geekery it contained.

Not all titles featured on BuddyTV are available through Amazon Prime.

Fillion was obviously in his element, but the delightful surprise was how much fun it was to see Beckett get in touch with her inner nerd. Beckett and Castle continue to be unbearably adorable and intensely fun to watch this season.

However I can't imagine how the show will beat the final moments of the episode, as Beckett finally dresses up in her sexy starship outfit topped with a terrifying mask to the smooth musical stylings of William Shatner.

Shiny!

It would take all day to name every Firefly reference, but the show starts off early by dropping the phrase "Shiny" casually into conversation. Later, Castle talks about that one Joss Whedon show that was really good. The star of Firefly obliquely mentioning Firefly on an episode parodying Firefly is so delightfully meta that my brain just about exploded.

Castle is at Supernova Con signing copies of his graphic novels to old dudes who look kind of like George Lucas. I guess it's a downgrade from the usual cute girl groupies he's used to. Of course, Beckett shows up and he offers to sign her book in a quite suggestive way. But instead Beckett explains there's been a murder at the convention and they go to investigate.

The murder centers around Nebula-9, a cheesy sci-fi show cancelled after only one season. The murder victim was running a Nebula-9 experience at the convention, in which the lead actor of the former show appeared to make the experience more realistic.

See Annabelle had been so into the show she had even bought the rights and made webisodes to continue on the show's storyline. That's dedication. Somewhere out there, a Browncoat is like "hmm!"

Zap! Said the Lady

It turns out Annabelle was killed by an actual replica laser gun, which is awesomely sci-fi. It's also an excuse for Castle to drop Fillion's catchphrase "Bam said the lady" only substituting the word zap.

It's like they wrote this episode by opening up the internet and just copying and pasting all the nerdy stuff into the script. Which is, obviously, awesome. There were references to Lord of the Rings, Watchmen, Battlestar Galatica, and Star Trek among others. It was like a Where's Waldo for nerd stuff. Spot the reference!

Because this is an episode of Castle, there are of course plenty of suspects. There's Captain Max, the washed up former star of Nebula-9 who is a drunken, STD-riddled mess. There's the best friends she starred in the webisode series with. There's Stephanie Frye, the former Lt. Chloe who finally managed to work her way up to be a "legitimate" actress. And then there's the weird guy she hooked up with at conventions. He of course dressed as a "creaver" which sounds an awful lot like Reavers, the scary monsters occupying the black in Firefly.

Each seems suspicious and has a motive for knocking off Annabelle. The most motivated seems to be her bestie, who found out she was going to sell the rights to the series she picked up cheap to a movie studio for two million dollars. A movie based off a failed one season sci-fi series? What will they think up next?!

Castle is more concerned that firing the phaser might be causing him to mutate and/or lose his hair. Espo, being a particularly bad wing-bro, notes that Castle couldn't really pull off the bald look. It's surprisingly refreshing that the show didn't pull out the other detectives finding out the Caskett secret forever. They seem pretty laissez-faire with flirting right in front of Ryan and Esposito now.

However, Castle's need to play with every gadget and fire every gun actually breaks the case wide open. The phaser left a residue on his hand that lights up in the proper lighting. So they bring everyone in and try them out. At first it seems like it's Captain Max, but in a hilarious twist it turns out he just bought another phaser and fired giant holes into his hotel room. That poor hotel cleanup staff.

The culprit was actually Lt. Chloe herself, who didn't want Annabelle to sell the rights. She didn't want to get pulled back into Nebula-9 after working so hard to claw her way out of the series. Couldn't she have just...I don't know...not signed on to the movie? Was murder really the only option here? She threatens Captain Max but he handily flips her over and she's off to jail.

K Becks

Perhaps the best part of the episode was getting to see Beckett get her nerd on. We've seen plenty of instances of Castle geeking out over the years, whether it's over Halloween costumes, laser tag, or zombies. But this is the first indication we've gotten that Beckett also has a hidden nerdy side.

In fact, she used to post on the Nebula-9 fansite and even dressed up as Lt. Chloe. Beckett in cosplay? Who would have guessed!? It was great to see the connection she had to this "silly" show and how much she loved her favorite character because of what she stood for.

Making an episode about sci-fi conventions and obsessed fans, it's easy for a show to go straight to a mean-spirited parody place. But Castle didn't go down that road. Instead, Castle showed that all the characters have a little bit of geekiness inside, from Castle's love of graphic novels to Ryan's appreciation of Lord of the Rings and Alexis' random bikini convention appearance. But Beckett's love for Nebula-9 was both unexpected and particularly adorable.

Best of all was the final shot of the episode, as Castle talks Beckett into donning her Lt. Chloe costume for him again in return for a whole Nebula-9 marathon, minus the snark. But Beckett, William Shatner, and her Creaver mask have the final laugh while Castle goes running.

What did you think of this week's episode? Did you love the sci-fi references or think they were too meta? Share some of the sci-fi references you caught in the comments!